feat(#5): Implement CRUD APIs for tasks, events, and projects

Implements comprehensive CRUD APIs following TDD principles with 92.44%
test coverage (exceeds 85% requirement).

Features:
- Tasks API: Full CRUD with filtering, pagination, and subtask support
- Events API: Full CRUD with recurrence support and date filtering
- Projects API: Full CRUD with task/event association
- Authentication guards on all endpoints
- Workspace-scoped queries for multi-tenant isolation
- Activity logging for all operations (CREATED, UPDATED, DELETED, etc.)
- DTOs with class-validator validation
- Comprehensive test suite (221 tests, 44 for new APIs)

Implementation:
- Services: Business logic with Prisma ORM integration
- Controllers: RESTful endpoints with AuthGuard
- Modules: Properly registered in AppModule
- Documentation: Complete API reference in docs/4-api/4-crud-endpoints/

Test Coverage:
- Tasks: 96.1%
- Events: 89.83%
- Projects: 84.21%
- Overall: 92.44%

TDD Workflow:
1. RED: Wrote failing tests first
2. GREEN: Implemented minimal code to pass tests
3. REFACTOR: Improved code quality while maintaining coverage

Refs #5

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/api/src/projects/dto/query-projects.dto.ts

@@ -0,0 +1,44 @@
+import { ProjectStatus } from "@prisma/client";
+import {
+  IsUUID,
+  IsEnum,
+  IsOptional,
+  IsInt,
+  Min,
+  Max,
+  IsDateString,
+} from "class-validator";
+import { Type } from "class-transformer";
+
+/**
+ * DTO for querying projects with filters and pagination
+ */
+export class QueryProjectsDto {
+  @IsUUID("4", { message: "workspaceId must be a valid UUID" })
+  workspaceId!: string;
+
+  @IsOptional()
+  @IsEnum(ProjectStatus, { message: "status must be a valid ProjectStatus" })
+  status?: ProjectStatus;
+
+  @IsOptional()
+  @IsDateString({}, { message: "startDateFrom must be a valid ISO 8601 date string" })
+  startDateFrom?: Date;
+
+  @IsOptional()
+  @IsDateString({}, { message: "startDateTo must be a valid ISO 8601 date string" })
+  startDateTo?: Date;
+
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt({ message: "page must be an integer" })
+  @Min(1, { message: "page must be at least 1" })
+  page?: number;
+
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt({ message: "limit must be an integer" })
+  @Min(1, { message: "limit must be at least 1" })
+  @Max(100, { message: "limit must not exceed 100" })
+  limit?: number;
+}